Vapor Deposition Film Manufacturing Apparatus

The present invention relates to a vapor deposition film manufacturing apparatus for manufacturing a high-quality metal vapor deposition film, which involves suppressing an adverse influence due to occurrence of unintended discharge while increasing the degree of adhesion of a dielectric film to a can-roller (cooling roller). More particularly, the present invention relates to a vapor deposition film manufacturing apparatus using a hollow cathode and thus not causing an increase in size of the apparatus.

Hitherto, as an apparatus for manufacturing a film for a film capacitor, that is, a metal vapor deposition dielectric film, there has been known an apparatus using a can-roller. In such an apparatus, a strip-shaped resin film being continuously supplied is fed while abutting against the can-roller in an area corresponding to a predetermined central angle (wrap angle), and metal vapor deposition is performed on the abutting portion.

The film is thin, and a temperature thereof substantially corresponds to a surface temperature of the can-roller. Thus, in order to prevent thermal damage of the film during the metal vapor deposition, a mechanism for cooling the can-roller is employed. Accordingly, a quality of a metal vapor deposition film is improved.

Moreover, when the degree of adhesion of the film to the can-roller is high, uniform and rapid cooling is achieved. Thus, a mechanism for charging the can-roller is also employed. The mechanism energizes a tungsten wire arranged so as to extend above the can-roller longitudinally in an axial direction of the can-roller, and the energization of the tungsten wire causes generation of thermoelectrons, thereby charging the can-roller.

Further, typically, an inside of a chamber is partitioned into an upper chamber and a lower chamber with the can-roller provided therebetween, and vacuum is adjusted so that the lower chamber in which metal vapor deposition is to be performed is maintained at a pressure of about 10Pa (Pa: pascal) or less, and the upper chamber is maintained at a pressure of about 10Pa.

In this case, a combination of, for example, a mechanical booster pump and a rotary pump is employed as a vacuum pump for the upper chamber, and in the lower chamber, an oil diffusion pump is further combined with those pumps, thereby achieving high vacuum.

In general, vacuuming in a larger number of stages is required as a vacuum degree is set higher. In a vapor deposition film manufacturing apparatus using a can-roller, substantially, two sets of vacuum pump systems for the upper chamber and the lower chamber, respectively, are required. This is because, compared to a case of introducing a vacuum pump system for setting a pressure of the entire inside of the chamber to about 10Pa or less without providing a partition therein, an increase in size of a configuration of the entire apparatus can be prevented, and it is possible to introduce the apparatus at low cost.

However, in the case of charging the can-roller, while it is required to emit electrons from a wire on the upper chamber side where the film is not wrapped, an atmospheric pressure is about 10Pa, resulting in a problem in that abnormal discharge occurs.

In order to avoid the problem, it is required to introduce a third vacuum pump system to set a pressure of at least only a vicinity of the wire to about 10Pa, or to introduce a large-sized pump system for setting a pressure of the entire upper chamber to about 10Pa at which abnormal discharge does not occur, resulting in a problem of eventually causing an increase in size of the apparatus configuration (as a result, the apparatus is also increased in cost).

The present invention has been made in view of the above, and an object thereof is to provide a vapor deposition film manufacturing apparatus for manufacturing a high-quality metal vapor deposition film without causing an increase in size of the apparatus.

A vapor deposition film manufacturing apparatus described in claimis a vapor deposition film manufacturing apparatus which is partitioned into an upper chamber and a lower chamber with a cooling roller, which is also called can-roller, having a circular column shape provided therebetween, the cooling roller being arranged so that an axis thereof is horizontal, and being configured to rotate to feed a dielectric film having a strip shape while causing the dielectric film to abut against the cooling roller over a predetermined central angle on the lower chamber side, the vapor deposition film manufacturing apparatus including: a evaporation unit, which is arranged in the lower chamber, and is configured to diffuse metal vapor toward the dielectric film; a lower-chamber vacuum pump, which is in communication with the lower chamber, and is configured to maintain the lower chamber at a first predetermined vacuum degree; an upper-chamber vacuum pump, which is in communication with the upper chamber, and is configured to maintain the upper chamber at a second predetermined vacuum degree; an electron supply chamber, which houses therein a hollow cathode, has a columnar outer shape, and is arranged so that a longitudinal direction of the electron supply chamber is parallel to the axis; a gas supply unit configured to supply gas for ionization into the electron supply chamber; chamber-inside pressure control unit for maintaining an inside of the electron supply chamber at a third predetermined vacuum degree; and a power supply unit configured to ionize gas inside the electron supply chamber via the hollow cathode. A slit for electron emission is provided in the electron supply chamber so as to be parallel to the axis, and is opened toward a portion of a surface of the cooling roller, which is not covered with the dielectric film. A prevention body is provided between the electron supply chamber and the cooling roller, and is configured to prevent electrons from diffusing to the upper chamber side due to rebound of the electrons from the cooling roller side. While adhesiveness of the dielectric film to the cooling roller is enhanced by charging the surface of the cooling roller, occurrence of unintended discharge in the upper chamber is suppressed.

That is, according to the invention of claim, there is used the electron supply chamber housing the hollow cathode, in which electrons ionized in an atmosphere with a pressure higher than the vacuum degree of the upper chamber are accelerated to be emitted. Thus, the degree of adhesion of the film can be suitably increased without causing an increase in size of the apparatus. In addition, electrons are suppressed from spreading inside the upper chamber due to rebound of the electrons from the cooling roller side. Thus, a possibility of occurrence of unintended discharge is reduced. Accordingly, it is possible to provide a metal vapor deposition film with a high quality and high reliability.

A size of the cooling roller is only required to be appropriately designed, and can be set to, for example, a diameter of from 50 cm to 70 cm, and an axial length (width) of from 350 mm to 950 mm. Further, in order that the cooling roller is efficiently charged, the surface thereof is preferably covered with a dielectric layer (insulating layer), and as an example, such a layer can be formed of ceramics. Examples of the ceramics may include only alumina, alumina and titania (a mixed ceramics of alumina and titania, part of alumina and titania may be changed to aluminum titanate), and only titania. The thickness of the insulating layer may be, for example, from 30 μm to 100 μm.

Examples of the material of the dielectric film may include polypropylene (PP), polyphenylene sulfide (PPS), polyvinylidene fluoride (PVDF), polyethylene terephthalate (PET), and polyimide. In addition, the thickness thereof may be, for example, from 1.5 μm to 50 μm, and the width thereof may be, for example, from 300 mm to 900 mm.

The first predetermined vacuum degree is only required to be a vacuum degree suitable for metal vapor deposition, and as an example, can be set to (0.5 to 50)×10Pa. The first predetermined vacuum degree is in an order of about 10Pa as a standard.

The second predetermined vacuum degree is only required to be appropriately designed in consideration of leakage of ionized gas from the electron supply chamber into the upper chamber, and a pressure difference between the upper chamber and the lower chamber, and as an example, can be set to (0.5 to 50)×10Pa. The second predetermined vacuum degree is in an order of about 10Pa as a standard.

Although depending on a slit width, a potential difference, a supply amount of gas, a vacuum degree of the upper chamber, and the like, as an example, the third predetermined vacuum degree can be set to from 0.5 Pa to 100 Pa. The third predetermined vacuum degree is in an order of about 10Pa as a standard.

As an example, the gas for ionization can be rare gas having poor reactivity with a film and a metal, for example, Ar.

A voltage from the power supply unit is not particularly limited as long as the voltage can cause gas to be efficiently ionized and also cause electrons to be accelerated so as to be continuously and stably injected from the slit. As an example, the voltage can be set to a DC voltage of from −4 kV to −16 kV with respect to a cathode (slit portion is grounded).

As an example, an interval of the slit can be set to from 0.1 mm to 1.5 mm. With this interval, electrons can be properly and continuously injected onto a portion of the surface of the cooling roller, with which the film is not in contact. Further, so to speak, a steady electron beam is supplied, and hence, even when electrons escape to the film side, an attraction force between the surface of the cooling roller and the film is kept, thereby enabling a high-quality vapor deposition film to be produced.

When the slit width is narrow, the electron beam substantially does not spread and linearly hits the surface of the cooling roller. A distance between the slit and the surface of the cooling roller can be set to, for example, from 20 cm to 30 cm.

A pressure PD of the lower chamber at the time of manufacturing a metal vapor deposition film is in an order of about 10Pa, and based thereon, a pressure and a size of each of places are determined, and the slit width is thus also determined substantially as an absolute value. However, a slit width “w” with respect to a sectional area S of the hollow cathode or the electron supply chamber satisfies 1,000≤S/w≤50,000 as a standard.

In this case, it is desired that all of electrons adhere to the surface of the cooling roller, but actually, rebound of a part of the electrons occurs. In this case, a portion in which electrons are liable to collect is sometimes generated due to a shape of the upper chamber and arrangement of each of parts, which causes abnormal discharge.

When a film is subjected to abnormal discharge, a vapor deposition film is naturally damaged, for example. Even when the film is not directly subjected to abnormal discharge, each of parts is affected, and degradation in quality of the film is indirectly caused.

Accordingly, the prevention body is provided for receiving such rebound of the electrons. For example, the prevention body can be formed as a prevention plate which is curved so as to follow an outer shape of the cooling roller. For example, the prevention body may be appropriately grounded, or the prevention body and the cooling roller may be brought into contact with each other so that the prevention body has a potential equal to that of the cooling roller.

According to the vapor deposition film manufacturing apparatus described in claim, in the vapor deposition film manufacturing apparatus described in claim, a guide body is provided in the upper chamber, and is configured to direct gas positively charged and leaked out from the slit, to a predetermined direction.

That is, according to the invention of claim, gas is transferred to the portion in which electrons are liable to collect, so as to eliminate a potential difference, and thus, occurrence of unintended discharge is further suppressed. Abnormal discharge may be prevented by intentionally causing gas to flow toward a portion in which it is particularly desired to prevent occurrence of abnormal discharge.

Even when the prevention body is provided, a part of electrons is diffused inside the upper chamber and collects in a portion in which electrons easily collect. The guide body causes gas positively charged and leaked out from the slit to direct to such a portion so that the portion is neutralized.

The guide body may be a plate-shaped directing plate, or may have a shape with a throttle as in a funnel. Further, the guide body may be also formed into a shape of a tubular directing port being in communication with the electron supply chamber and extending from the slit side (while preventing interference of the guide body with an electron beam).

It is preferred that the guide body be arranged in a vicinity of the slit, and the prevention body be arranged in a vicinity of the cooling roller. However, the guide body and the prevention body may be formed as an integrated body such that the guide body serves as an upper surface and the prevention body serves as a lower surface.

According to the vapor deposition film manufacturing apparatus described in claim, in the vapor deposition film manufacturing apparatus described in claimor, the dielectric film caused to abut against the cooling roller is a dielectric film having one side which has already been subjected to metal vapor deposition with a metal identical to or different from a metal of the metal vapor, and the central angle is a predetermined central angle of more than 180° and 270° or less.

That is, according to the invention of claim, it is possible to manufacture a high-quality double-sided metal vapor deposition film or a high-quality single-sided multi-layer metal vapor deposition film.

When two cooling rollers are provided in the same apparatus, and metal vapor deposition is first performed on one side of the film, even if heat remains on the film, a wrap angle can be set larger, and the film can be suitably caused to adhere to the cooling roller, thereby preventing degradation in quality of the film due to thermal damage of the film at the time of second vapor deposition.

Further, even when only one cooling roller is provided, and second (or subsequent) metal vapor deposition is performed, stable vapor deposition is achieved without heating a metal membrane which has already been vapor-deposited.

According to the vapor deposition film manufacturing apparatus described in claim, in the vapor deposition film manufacturing apparatus described in claimor, the chamber-inside pressure control unit is a unit for adjusting a supply amount of gas of the gas supply unit, or is a vacuum pump provided for the electron supply chamber.

That is, according to the invention of claim, it is possible to perform pressure control in a simple manner. In particular, when the unit for adjusting a supply amount of gas is formed of a valve (and a flow meter), an apparatus configuration is simplified.

In the vapor deposition film manufacturing apparatus described in claim, in the vapor deposition film manufacturing apparatus described in claimor, the cooling roller is charged so that a pressure PD of the lower chamber, a pressure PU of the upper chamber, and a pressure PR of the electron supply chamber satisfy PD<PU<PR and 10PU≤PR≤1,000PU.

That is, according to the invention of claim, it is possible to maintain the cooling roller in a steady and proper charged state.

As shown in the examples above, PD: an order of 10Pa, PU: an order of 10Pa, and PR: an order of 10 Pa can be each taken as a standard.

According to the present invention, it is possible to manufacture a high-quality metal vapor deposition film by suitably and continuously charging the can-roller without causing an increase in size of the apparatus.

Hereinbelow, with reference to the drawings, detailed description is given of an embodiment of the present invention. Here, description is given of a vapor deposition film manufacturing apparatus for performing metal vapor deposition on both sides of a film.

is a sectional view for illustrating a configuration example of a double-sided vapor deposition film manufacturing apparatus to which a vapor deposition film manufacturing apparatus of the present invention is applied.

For convenience of description, the double-sided vapor deposition film manufacturing apparatus is hereinafter simply referred to as “double-sided vapor deposition apparatus.”

A double-sided vapor deposition apparatushas a configuration mainly including a first vapor deposition unit, a second vapor deposition unit, a delivery/take-up unit, an upper-chamber vacuum unit, a lower-chamber vacuum unit, and an electron supply unit.

Of those, the first vapor deposition unit, the second vapor deposition unit, the delivery/take-up unit, and a part of the electron supply unitare housed in a chamber.

The chamberis partitioned by partitionsinto an upper chamberU and a lower chamberD with a can-rollerand a can-roller, which are described later, provided therebetween.

The first vapor deposition unitincludes the first can-rollerand a first evaporator.

The second vapor deposition unitincludes the second can-rollerand a second evaporator.

The delivery/take-up unitincludes a delivery roller, a take-up roller, a first restriction roller, second restriction rollers, and a plurality of auxiliary rollers.